Advanced GIS for UCCE Analysis

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Advanced GIS for UCCE - Analysis

• August 22, 2007
• Maggi Kelly
• Department of Environmental Science, Policy, and
  Management
• Karin Tuxen-Bettman
• GIIF
• http//giif.cnr.berkeley.edu

We will begin at 110 PM. Login info Username
!workshopuserPassword 1WRKshop USR!Domain
CAMPUS
Geospatial Imaging Informatics Facility College
of Natural Resources _at_ UC Berkeley
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This Afternoons Outline

• Overview of specific GIS analysis
• Spatial statistics
• Landscape ecology
• Hydrologic modeling and watershed delineation
• Examples of spatial analysis in natural resource
  science and ecology
• Overview of land cover datasets
• Other software for integrated statistical
  analysis
• Spatial analysis and statistics tools in ArcGIS
  9.2
• Computer exercises Choose from 1 or more
  applications, including
• Map measure polygonal clusters and patterns
• Measure point patterns and distributions
• Hydrologic modeling and watershed delineation
  using the Model Builder
• Using Google Earth for 3D visualization

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What are Spatial Statistics?

• Spatial statistics are not traditional statistics
  about things that happen to have spatial
  component
• Spatial statistics take space into account, e.g.
  distance.
• Two types
• Descriptive characterizes pattern
• How are points distributed?
• What is the pattern?
• Where are the clusters?
• Quantitative quantifies/measures pattern
  (e.g. pattern, relationships, trends)
• How clustered/dispersed is the data?
• What are the relationships with other data?

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What is Landscape Ecology?

• Spatial pattern is linked to ecological process
• i.e. Turner, Forman and Godron, etc.
• A landscape is made of
• Structure
• Patch, corridor, mosaic
• Size, shape, spatial configuration
• Function
• Population dynamics, nutrient cycling,
  competition, succession, physical processes
• Change
• Anthropogenic change
• Natural change

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What is Hydrologic Modeling Watershed
Delineation?

• Hydrology concerns the movement of water across a
  surface, the flow of water through a drainage
  system

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Methods for performing GIS analysis

• Ask your question,
• Collect your data,
• Choose a GIS analysis method,
• Calculate the statistic(s) and/or metrics,
• Interpret the statistics, and
• Test significance.

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Land Cover Datasets

• Multi-source Land Cover Dataset (2002, 2006)
• Source CDF (http//frap.cdf.ca.gov/data/frapgisda
  ta/select.asp)
• Spatial resolution 100 meter (2002), 30 m (2006)
• Landfire dataset (2005)
• Source USGS (http//www.landfire.gov/products_ove
  rview.php)
• Spatial resolution 30 m
• Coastal-Change Analysis Project (2002) coastal
  counties only!
• Source NOAA (http//csc.noaa.gov/crs/lca/pacificc
  oast.html)
• Spatial resolution 30 m
• National Land Cover Dataset
• Source USGS (http//edcftp.cr.usgs.gov/pub/data/l
  andcover/states/)
• Spatial resolution 30 m
• CalGAP (1986)
• Source UCSB CalGAP Project (http//www.biogeog.u
  csb.edu/projects/gap/gap_data_state.html)
• Spatial resolution 4 ha MMU
• CalVeg77 (1977) (http//frap.cdf.ca.gov/data/frapg
  isdata/select.asp)
• Wieslander Vegetation Type Mapping Project
  (1920s) (http//vtm.berkeley.edu)

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Measuring Geographic Distributions(e.g. How are
the points distributed?)

• Mean
• Median
• Central feature

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Spatial Statistics
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Spatial Pattern Analysis

• Pattern of point distribution
• Nearest neighbor index
• Ripleys K
• Theissen polygons, or Voronoi diagrams
• Semi-variogram
• Quadrat analysis
• Pattern of point and polygon values
• Continuous data gradients and localized
  variability
• Morans I
• Getis-Ord General G
• Kriging
• Discrete/categorical data
• Landscape pattern metrics
• Join count

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PATTERN OF POINT DISTRIBUTIONNeighborhood
Operations

• What is close to me?
• Methods
• Straight-line distance (Euclidean distance)
• Spider diagram
• Distance of cost over network
• Cost over a surface
• Buffers
• Variable distance buffers
• Filters
• Local, Focal and Zonal functions
• Distance to/from features
• Theissen polygons, or Voronoi diagrams

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PATTERN OF POINT DISTRIBUTIONNearest Neighbor
Index

• Calculates the average distance between points
• Significance is tested with Z-score
• Types
• Inter-centroid distance
• Boundary-boundary distance

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PATTERN OF POINT DISTRIBUTIONRipleys K Function

• Counts the of features within defined distances
• Measures spatial arrangement (clustered,
  uniform, random)
• Uses multiple simulations to create arandom
  distribution envelope
• Detect the scale of those patterns,e.g. what is
  the cluster size?
• Assumes
• Stationary No trends in the data
• Isotropy No directional detection (although it
  is possible to modify the K function to detect
  anisotropy.
• Regular study area (rarely encountered)

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PATTERN OF POINT DISTRIBUTIONRipleys K function
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Spatial Autocorrelation

• Spatial autocorrelation measures the level of
  interdependence between the variables, the nature
  and strength of the interdependence
• Can be either positive or negative
• Positive spatial autocorrelation has all similar
  values appearing together, while negative spatial
  autocorrelation has dissimilar values appearing
  in close association (less common)
• Measured by
• Semivariograms
• Morans I
• Gearys C

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PATTERN OF POINT DISTRIBUTIONSemivariograms
semivariance
sill
nugget
h
range

• Range the average distance within which the
  variable remains spatial autocorrelated ? the
  extent of spatial trends, distance beyond which
  sampling is random
• Sill the maximum variance of the sample data
• Nugget measurement errors or smaller variations
  within the minimum sampling distance ? the noise
  in the data

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PATTERN OF POINT DISTRIBUTIONSemivariograms
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PATTERN OF POINT DISTRIBUTIONSemivariograms
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PATTERN OF POINT POLYGON VALUESMorans I

• Shows similarity of neighboring features
• Provides a single statistics summarizing pattern
• For continuous data
• Spatial covariation/total variation
• Ranges from 1 to 1
• Positive positive spatial autocorrelation,
  negative represents negative autocorrelation. 0
  no spatial autocorrelation (random).

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PATTERN OF POINT POLYGON VALUESGetis-Ord Gi
and General G

• Hot-spot analysis, showing concentration of high
  or low values
• Indicates whether high or low values are
  clustered
• Uses a neighborhood based on a distance you
  specify
• Applies a weight to those within the distance
  that have similar values

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Other Software for Statistical Analysis

• Fragstats
• http//www.umass.edu/landeco/research/fragstats/fr
  agstats.html
• ArcGIS Geostatistical Analyst
• http//www.esri.com/geostatisticalanalyst/
• GEODA
• Great for categorical (and other!) pattern
  analysis
• FREE https//www.geoda.uiuc.edu/
• VARIOWIN
• Great for semi-variograms
• FREE http//www-sst.unil.ch/research/variowin/
• R
• FREE http//www.r-project.org/
• S spatial statistics module
• NOT FREE http//www.insightful.com/products/spati
  al/
• SAS
• NOT FREE http//www.sas.com/technologies/analytic
  s/statistics/

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PATTERN OF POINT POLYGON VALUESLandscape
Pattern Metrics

• Landscape Ecology uses pattern metrics to
  quantify structure
• Size
• Patch size
• Shape
• Elongated, circular, amount of edge
• Spatial configuration
• Measuring patterns in the mosaic (patch metrics)
• Clustered, dispersed
• Dominance, linkages, isolation, proximity
• Fragmentation, isolation, connectivity

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ArcGrid enabled Fragstats
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Landscape MetricsONE metric per site
(landscape)
Whole landscape
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Class MetricsONE metric per class in the map
Each color represents separate class
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Patch MetricsONE metric per patch (landscape)
Each patch metric calculated for each patch
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Problems with Pattern Metrics

• There has been much scrutiny of these techniques,
  and criticism, including
• Metrics are highly redundant
• Metrics are very sensitive to inputs and to scale
• Conceptual flaws in landscape pattern analysis
• Unwarranted relationships between pattern and
  process
• Quantifying pattern without considering process
• Ecological irrelevance of landscape indices
• Two recent papers discuss these issues and more
• Wu, J. 2004. Effects of changing scale on
  landscape pattern analysis scaling relations.
  Landscape Ecology 19 125-138.
• Li, H., and J. Wu. 2004. Use and misuse of
  landscape metrics. Landscape Ecology 19 389-399.

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Definitions

• Drainage system
• Area upon which water falls, and the network
  through which it travels to an outlet
• Drainage basin
• Area that drains water to a common outlet
• This area is normally defined as the total area
  flowing to a given outlet, or pour point.
• Other common terms for a drainage basin are
  watershed, basin, catchment, or contributing
  area.
• Outlet, or pour point
• Point at which water flows out of an area
• Usually the lowest point along the boundary of
  the drainage basin
• Drainage divide or watershed boundary
• The boundary between two basins

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Definitions

• Network
• Outlet
• Stream channels
• Junction, or node
• Intersection of two stream channels
• Interior links
• Sections of a stream channel connecting two
  successive junctions, or a junction
• Exterior links
• Outermost branches of the tree, (i.e., they have
  no tributaries).

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Hydrologic Analysis
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Flow Direction

• The output of this request is an integer Grid
  whose values range from 1 to 255. The values for
  each direction from the center are
• For example, if the direction of steepest drop
  was to the left of the current processing cell,
  its flow direction would be coded as 16.

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Flow Accumulation

• Flow Accumulation creates a grid of accumulated
  flow to each cell, by accumulating the weight for
  all cells that flow into each downslope cell.
• Hydrography is usually created with a threshold
  of accumulated cell values.

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Hydrology Tools in ArcToolbox

• Watersheds basins
• Snap Pour Point
• Stream to Featuresimplify vs. non-simplify
• Stream Order

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Data for Hydrological GIS

• Elevation
• SF Bay Area Regional Database (BARD) 30m and some
  10m DEMs http//bard.usgs.gov
• SF Bay NGA 2m DEM see GIIF
• California 90m DEM see GIIF
• National Elevation Dataset (NED) 30m DEM
  http//ned.usgs.gov
• North America 1,000m DEM (ESRI) see GIIF
• Global 1km GTOPO30 (USGS) http//edcdaac.usgs.go
  v/gtopo30/gtopo30.html
• Stream gage data (daily and real-time)
• USGS National Water Information Systems (NWIS)
• Watersheds, water districts, rivers
• Calif. Spatial Information Library (CaSIL)
  http//gis.ca.gov
• U.S. National Hydrography Dataset (NHD)
  http//nhd.usgs.gov/

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Elevation Data
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